An improvement on stock RTG behavior with its eternal power supply.
Implements a configurable, robust mechanism for Radioisotope decay and power generation.
Parts with ModuleDiminishingRTG will be able to configure their isotope fuel from within the VAB, a single input being reflected across all symmetry companions.
Parts should behave consistently between vessel docking/undocking.
Decay operates in background (all unfocused vessels).
Can be added to any part without interference... probably.